Acropora Eating Flatworm AEFW

AEFW are in my opinion the worst pest to encounter within a reef tank. They are extremely challenging to eradicate and leave most people feeling drained, as they are relentless.

Some people like to blame shops or other reefers for getting infected with AEFW. This blame culture never ceases to amazes me! I have had AEFW twice before in previous tanks and, the person I blame is me. I am at fault. Not the shop who I bought the coral off. We must take full responsibility for everything that happens within our tanks – good or bad. We have total control of what we put into the aquarium, be that nice or horrid.

I am highly reluctant and genuinely fearful of adding any acropora to my tank, without it being quarantined for at least 6 weeks first. During quarantine, it is important to assume the coral has AEFW, even if you can’t detect any and, treat accordingly.

If for what ever reason you don’t quarantine acropora, at the very least I would recommend using a coral dip, my preferred choice is Revive Coral Cleaner, made by Two Little Fishes. This dipping procedure should also be used during quarantine. Follow the manufacturers instructions for dosing and, whilst the coral is in the dip, use a turkey baster to blast the acroporas ensuring that the dip is vigorously jetted into all areas of the coral, I turn the coral over and make sure every part of the acropora is thoroughly subjected to the water and dip mix. I would also recommend removing the coral base and any stripped branches, as this is where AEFW lay their eggs. Eggs will not be laid on coral flesh.

As a minimum I would recommend dipping acroporas twice a week during quarantine (dip every 3-4 days, say every Sunday and every Wednesday) for at least 6 weeks. 8 weeks is better. When dipping the de-based corals inspected for any eggs, also examine the dip after dipping for signs of AEFW (remember babies are tiny).

There are at least two types of AEFW. Possibly many more.

AEFW will not be detected by the naked eye, whilst on the corals in your tank, although you may notice some very small bite marks.

Here is an infected acropora with typical bite marks

Here are the AEFW eggs:

Here’s a close up of AEFW

Here’s some AEFW removed in a dip

It’s not until after you get infected, the hassle of dealing with AEFW makes you wish you had quarantined your acropora before adding to the main aquarium – quarantine is far less hassle in the long run!

These are not to be confused with red planaria flatworms which look similar. Salifert flatworm exit has no effect on AEFW even when used at over-dose rates.

Biological control methods include a variety of wrasse, peppermint shrimps, arrow crabs, camel shrimps and various other predatory fish and inverts.

Acroporas that host commensal crabs, especially the smooth white shell crabs with a black mask, a very rarely plagued by AEFW.